Parallel link robot connected by ball joints

Abstract

A parallel link robot ( 10 ) including ball joints ( 42 a to 42 d ) which are arranged between driven links ( 22 a, 23 a ) and a drive link ( 21 a ) and between a driven link and a movable part ( 12 ), at least one of these ball joints including a ball ( 44 a ) and a housing ( 42 a ) which covers at least half of the surface of the ball including the maximum diameter part and further including with a covering part ( 45 a ) which covers the area around the ball of the ball joint.

The invention claimed is: 
     
       1. A parallel link robot, comprising:
 a base part; 
 a movable part; 
 three link parts which link said base part and said movable part and respectively have single degrees of freedom with respect to said base part; and 
 three actuators configured to drive the respective link parts, 
 wherein each of said link parts comprises
 a drive link which is linked with said base part, and 
 two driven links which link said drive link and said movable part and are parallel with each other, 
 
 wherein the parallel link robot further comprises ball joints which are arranged
 between said driven links and said drive link, and 
 between said driven links and said movable part, 
 
 wherein each of said ball joints includes a ball and a one-piece housing which covers a maximum diameter part of said ball, a first part of a surface of the ball at one side of the maximum diameter part and a second part of the surface of the ball at another side of the maximum diameter part, 
 wherein the parallel link robot further comprises
 a covering part which seals and covers the area around said ball of said ball joint; 
 two elongated plates which link said two driven links of said link part; 
 rotary shafts by which the two elongated plates are linked with said two driven links of said link part; and 
 two spacers which are arranged between the two elongated plates, and are spaced from each other and from the rotary shafts along a longitudinal direction of the two elongated plates, and 
 
 wherein 
 the two elongated plates are arranged in parallel with each other by the two spacers between the two elongated plates, 
 the two elongated plates are pivotable, with respect to the driven links, around the rotary shafts, 
 the two elongated plates are positioned closer to a linking part between the drive link and the two driven links than the moveable part, 
 each of the two elongated plates further comprises an opening elongated in the longitudinal direction of the elongated plate, 
 the elongated plates are configured to maintain a distance between the driven links constant, 
 the housing of each of said ball joints has an extended part extending away from the ball of said ball joint, the extended part has a threaded part engaged with a corresponding threaded part at an end of the corresponding driven link, and the threaded parts are configured to adjust a center distance between the two ball joints coupled to said driven link, and 
 the driven links are not connected to each other between the elongated plates and the moveable part. 
 
     
     
       2. The parallel link robot as set forth in  claim 1 , wherein
 the covering part has a conical shape tapering toward the drive link. 
 
     
     
       3. The parallel link robot as set forth in  claim 1 , wherein
 the covering part has a serpentine shape for improving trackability and flexibility of the covering part. 
 
     
     
       4. The parallel link robot as set forth in  claim 1 , wherein
 each of the elongated plates has two elongated openings elongated in the longitudinal direction of the elongated plate, and 
 the spacers are arranged, in the longitudinal direction of the elongated plate, between the two elongated openings. 
 
     
     
       5. The parallel link robot as set forth in  claim 4 , wherein
 the covering part has a conical shape tapering toward the drive link. 
 
     
     
       6. The parallel link robot as set forth in  claim 4 , wherein
 the covering part has a serpentine shape for improving trackability and flexibility of the covering part.